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The Unexpected Benefits of Exercise: Past, Present, and Future

By Brian Schilder

December 29, 2016

“If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health.” ~Hippocrates

What Does Exercise Do For You?

The notion that exercise is good for you isn’t exactly breaking news. The role of physical activity as an integral component of a healthy lifestyle is a concept that is engrained into our collective consciousness (and rightfully so). What may be surprising is the breadth and degree that those benefits span. Most people are familiar with the vital role of exercise in reducing risk for cardiovascular disease, stroke, type-II diabetes, obesity, muscle atrophy, bone density loss, asthma, arthritis, various forms of cancer and longer overall life expectancy [1]. However evidence continues to accumulate that the benefits of exercise extend to virtually every system in the body (mediated in part by wide-spread changes in gene expression [2,3]) including the improvements in immune functioning, bone marrow stem cell regeneration, inflammation, insomnia, migraines, the volume of brain structures, cognition, psychological well-being, and many other aspects of human health [1,4]. The benefits of exercising today can extend far into future years, as recent studies have found associations between exercise earlier in life and healthy aging in the same individuals followed over time.

But what if you’ve never been a big exerciser and the find yourself feeling as though the opportunity to receive the benefits of exercise are well past you? Quite to the contrary, exercise plays an even more important role in health as one gets older, holding the potential for profound effects with even moderate efforts. In senior adults (The New York Times, National Institute on Aging), exercise has been shown to be one of the most effective treatments of age-related physical and mental decline. In one study, the benefits were such that exercise didn’t just slow the rate of natural brain structure shrinkage and memory decline in aging subjects, it actually began to reverse them over a period as short as 1-2 years [5]. Similarly many of those already afflicted with degenerative diseases such as Alzheimer’s disease and Parkinson’s disease have shown improvements of their symptoms over the course of exercise interventions [6,7]. Despite all of our medical advancements over the millennia, exercise remains one of the most effective (not to mention financially accessible) means of preventing a wide variety of preventable illnesses. And while exercise is far from being the cure-all replacement for all clinical conditions, it can often be used in tandem with medical treatments to maximize the chances of a swift and successful recovery (depending, of course, on the nature of the condition and the recommendations of one’s medical practitioner).

Exercise Across the Animal Kingdom

The health-promoting effects of exercise have deep evolutionary roots. Even baby alligators benefit from brisk jogs on a treadmill [8]. In fact, almost any species that is adapted for movement requires a certain degree of physical activity to remain in a non-pathological state [9]. When experimental lab mammals (e.g. mice) are exercised their physical fitness as well as performance on cognitive tasks significantly improve [6]. Similarly, wild-raised animals have enhanced cognitive and neural health compared to lab-raised conspecifics, which is in no small part due to differences in exercise [10–13]. This has led some to claim that exercised animals should be considered the “control” condition and should therefore be used in all research. However, perhaps unsurprisingly, species evolutionarily adapted for different ecologies require different degrees and forms of regular exercise. For example, the three-toed sloth might typically dawdle around little more than 10 meters2 in the wild, whereas the long-ranging wolf occupies a home range spanning upwards of 22,000 meters2 [14]. Thus, it would be wrong, and rather inhumane, to confine a restless wolf to a habitat ideal for a sleepy sloth. Our egos aside, humans are animals too, shaped and molded by evolutionary forces into our current form. Amongst the many features that differentiate our species from our closest non-human primate relatives, are those that bequeath us with an unusual capacity for long-distance mobility (e.g. bipedalism, increased hind limb length, superior sweating ability) [9,15]. Interestingly, wolves and humans share similarities in their physiological responses to exercise in contrast to other species, perhaps indicating convergent adaptations for long-distance mobility [16]. In human evolution, this was likely related increasingly sparse distribution of vital resources (food, water, mates) [9,17]. These factors and others culminated in a strange, upright primate with an unusual capacity for long-range mobility. Much like the tale of the sloth and wolf, humans may require different degrees and types of exercise compared to our closest living non-human primate relatives in order to remain healthy [18].

The Practicalities of Exercise in the Modern World

So exercise is important. In many ways it may even be especially important for humans (relative to some other species). Now how do we actually get it? The typical workday of many industrialized society citizens involves long hours sitting at a desk, tapping away on glowing machines with our dexterous appendages. In the course of writing this blog article on the virtues of exercise I’ve spent many hours remaining stationary, a factor that is highly correlated with risk for coronary heart disease, stroke, cancer, and countless other non-infectious diseases in human populations across the globe [19]. Yet I felt it was a necessary price to pay in order to achieve my non-(personal)-health related goals. Indeed, many of us recognize that the level of exercise that we may be evolutionarily adapted for (2-4 hours of exercise per day, as some have estimated based partly on observations of modern hunter-gatherers [1,20]) is not always entirely compatible with our other aspirations in life. Nor is it necessarily even the case that the exact activity our bodies are evolutionarily adapted for is ideal for human health [20]. Even the less-demanding recommendations put forth by the U.S. Department of Health (30 minutes of exercise per day, 3 days per week) may seem unrealistic for many. Balancing physical health, success at work, and all other aspects of one’s life demands a level of time management skills that many of us struggle to achieve. This is perhaps especially true in professions that do not necessarily adhere to a 9-5-work schedule. One such profession is academia, where there is often tremendous pressure for both students and staff to put in hours well beyond the typical workday and “overtime” becomes the culturally accepted norm.

So rather than each one of us aiming to become the paragon of human fitness, for most the question realistically becomes, “How much do I have to exercise to minimize my risk of disease while still achieving my other life goals?” In this light, these goals may not be locked in eternal battle quite to the extent that we may think. Based on a brief survey of my personal experiences, international health guidelines, and the literature at large, here I attempt to provide here some ideas as to how to balance work and health. Some of these may be familiar or obvious to readers (though perhaps still good reminders), but my hope is that at least some will urge others to find new ways of incorporating exercise into a healthy lifestyle.

1. Consistency Over Intensity: For many the concept of exercise brings to minds images of intense strain writ in red faces and exhausted gasps. While these can be signs of a particularly vigorous and beneficial workout, for others this stressful imagery may serve as a mental barrier as they contemplate getting into a routine (particularly those with, say, low current levels of fitness and/or pre-existing heart conditions). Working out with the intensity of a adrenaline-infused bull once every two months is highly unlikely to be nearly as beneficial as consistently exercising every day or every other day, even with low-intensity exercises such as long walks (though read here for new research on the potential benefits of high-intensity, short-duration exercise).

a. Science Tidbit: Investigating the neurobiological basis of motivation to exercise is an area of study that has more recently gained momentum. While finding the most effective way to reinforce healthy exercise habits is still a matter of active study, endocannabinoid, opioid, and dopamine neurotransmitter systems (the same systems involved in certain drug reward responses) play large roles [9,21].

2. Doing What You Enjoy: On that note, engaging in exercise that seems manageable, not overly stressful, and ideally enjoyable will bear the highest likelihood of you continuing with it in the long-term (being super fit for only a couple years is probably less beneficial for your cumulative lifetime health than remaining moderately fit throughout the majority of your life). For this reason it’s important to find a form of exercise that you enjoy. Treadmills aren’t for everyone, and other activities such as walking, hiking, climbing, tennis, biking any other number of activities can have substantial benefits if done regularly.

a. Science Tidbit: Forcing yourself to constantly do exercise that you absolutely hate still has its benefits, but animal models that freely choose to exercise show greater gains in physical and cognitive health than those that are forced to run on treadmill [22,23].

3. Knowing When to Take a Break: It’s easy to underestimate the power of short periodic breaks to walk around throughout the workday, but these bouts of exercise can accumulate and have significant effects on physical health. Taking a step back also provides the mental break that is often necessary to get past writer’s block or find a creative solution to a stubborn problem.

a. Science Tidbit: Recent research has found that these kinds of insights are significantly enhanced by exercise, both in the short-term and the long-term. Thus, taking breaks at key periods of low productivity can ultimately save time and avoid unproductive head-banging.

4. Commuting More Efficiently: Commuting in traffic is never fun. For DMV area residents it has become even less fun with significant increases in delays and closures to the Metro system. Biking can provide an alternate and often faster means of reaching your destination. For example, a 45-60 minute metro ride from Petworth, DC to Foggy Bottom can be turned into a 15-20 minute bike ride. For a round-trip daily commute that adds up to a lot of your life. Cutting down on brutal commute times ultimately reduces stress and provides more time to get things done, inside and outside of work.

a. Science Tidbit: Biking as opposed to taking the Metro saves me about 1 hour per day. Compounded over a year, assuming I commute to the office 5 days per week, and taking away of month of travel and holiday breaks, this saves me about 242 hours (~10 days) per year. That’s 10 days of my life I will gladly reclaim from the DMV Metro system. Not really science so much as basic arithmetic, but hey it gets the point across.

5. Being Social: Many of these are things that can be done socially as well, which has the multifaceted benefits of making the activities more enjoyable, providing a positive source of peer pressure to continue in the long-term, and dual-purposing exercise time catch up with friends.

a. Science Tidbit: We are highly social primates, and finding opportunities to spend quality time with friends and family can be a challenge. In both humans and non-human animals social enrichment offers a whole host of benefits including increased socially-bonding oxytocin release, decreased cortisol levels, and improved memory [24–26], all of which are also effects of exercise (providing a double whammy of neurochemical joy).

These are just some ways in which our desires to achieve physical/mental well-being and professional success are not necessarily in direct opposition with one another. In some tasks exercise even goes so far as improving cognitive performance more than cognitive training itself [6]. When you devote precious time to exercise, you may actually be indirectly getting some of that time back through improvements in energy-regulation/mental stamina, concentration, memory, productivity, creativity, and general happiness (which will in turn affect all the others) [1,6]. That last point is not small one given the alarming prevalence of excessive stress and mental illness in academia (see also a highly relevant article by fellow student Meagan Vakiener). Exercise (along with proper nutrition and sleep) may be especially important for those pursuing this professional avenue as a wealth of literature has demonstrated that regular exercise can be instrumental in improving and maintaining mental health. It remains one of the most effective means of treating depression and anxiety, even acting on many of the same neurochemical pathways targeted by the most commonly prescribed anti-depressant medications [27–30].

In short, I encourage those who struggle to find time and energy to devote towards exercise to consider its diverse and perhaps unexpected physical and mental benefits. Your future, present, and ancient past selves will thank you for it.